Copper base alloy



Patented Dec. 14, rear COPPER BASE ALLQEI' Charles H. Davis, Cheshire, and Elmer ll. Munson, Naugatuck, Conn, assignors to The Amen ican Brass Company, Waterbury, Donn, a cor poration of Connecticut "W No Drawing. Application April 13, E1035,

Serial No. 16,204

9 Claims. (01. les -32 This invention relates to an improvement in copper base alloys and particularly to an alloy whose principal constituent is copper plus various amounts of nickel, aluminum and zinc, accompanied in the present invention by small but essential amounts of cadmium.

Alloys have been made heretofore consisting essentially of copper, nickel, aluminum and zinc, with and without small amounts of manganese purposely added and are-in use because of their valuable properties. The composition range of these alloys is approximately Percent Copper 60. to 98.5 Nickel -1. .5 to 30.

Aluminum"; .5 to 4. Zinc .5 to 39. v Manganesefl -l 0. to 1.

We have discovered that when small amounts of cadmium from about 05% toabout 3.% are purposely added to these copper-nickel-aluminum-zinc alloys, new and valuable characteristics are obtained not heretofore found in said alloys.

An alloy or alloys made in accordance with the 'present invention are suitable for the same uses as the previously mentioned copper-nickel-alumihum-zinc alloys, and in addition have several new uses hereinafter mentioned. A considerable improvement in corrosion resistance, and especial- 'ly resistance to oxidation at all temperatures below 500 0., is obtained with our improved alloy or alloys. 7 g A very important advantage of an alloy embodying the essential features of 'the present invention is the excellent resistance which they of-" fer to attack by corrosion. The improved a1- loys are almost impervious to intercrystalline attack or corrosion when exposed to steam and hot water under pressures as high as 130 lbs/sq. in. for long periods of time. This strong resistance to corrosion was found in the im proved alloys even when stressed up to 80 per- L5 cent of the ultimate tensile strength in a steam chamber with the steam pressure maintained at about 130 lbs. per sq. in." For example, an old a type alloy wire containing about 65 percent copper, 5 percent nickel, 1.5 percent aluminum. and

, 28.5 percent zinc, when tested in steam with a load equal to80 percent of the ultimate tensile strength, as mentioned above, remained in the steamchamber only four hours before breaking.

An improved alloy wire similar to the above,- except that it contained about 0.50 percent cad mium, lasted 48 hours in the steam chamber before failure with a load equal to 80 percent of the ultimate tensile strength.

The improved alloys possess valuable corrosion resistance properties that are especially suitable for use in steam expansion joints, condenser tubes, flexible metal hose, welds, valves, tanks and the like and are also valuable for general structural and fabricating purposes.

After annealing or heat treating these im- 10 proved alloys, the presence of a thin, light-brown film was noted on the surface of the wire. This film was also noted on annealed wire which had been pickled in dilute sulphuric acid (1 to 10),

thoroughly rinsed in water and dried in an oven 5 at about 100 C. This film appears to afford some protection against intercrystalline attack or corrosion, and is definitely associated with the presence of cadmium in the alloy.

Another very important advantage of an al- 10y embodying the essential features of the present invention is the great increase in tensile strength and hardness that may be. obtained by heat treatment at low temperatures when the nickel content exceeds 3.0 percent and the aluminum content exceeds 0.50 percent. For example, such an alloy hot rolled and finished by the usual methods of cold rolling and annealing, had a tensile strength, cold drawn, of.126,500 lbs. per sq. in. After heat treating two hours at approximately 350 C. the tensile strength of the said cold drawn wire was increased to'152,900 lbs. per sq. in. Specimens of said wire when annealed at approximately 825 C. for 1 hour and quenched had a tensile strength of 70,400 lbs.

per sq. in. which, after heat treatment for two sistance to fatigue of the hardened alloy made according to our invention as opposed to low percentage elongation or brittleness which is found in several age hardened alloys.

The importance of this age hardening or precipitation hardening is readily apparent. Articles may be fabricated from the annealed or V wrought alloy and whenfinished, may be hardened by low temperature heat treatment. Be-

' cause the alloy is not susceptible tov softening at temperatures up to 500 C., it is suitable for condenser tubes, parts for'internal combustion engines-and other uses subject to operating temperaturesbelow 500 C. The resistance of this alloy to wear, when hardened, is noteworthy.

An alloy made in accordance with the present invention comprises as essential ingredients the following metals; in about the ranges of composition stated:

- Percent Copper 60. to98.7

Cadmium .05 to 3.0

Nickel .5 to 30.0

Aluminum .25 to 4.0

. Zinc 1 .5 to 39.2

Manganese" 0. 'to 1.0

may be and usually is some iron present.

from 0.01 percent to Because it cannot be avoided without too much expense in refining the constituent metals, there The iron content usually varies about 0.20 percent.

Manganese in small amounts is oftentimes purposely added to these alloys, essentially for insofar as corrosion resistance and age hardenlug-are concerned, and it may be omitted.

Thegreat increase in hardness is obtained only when nickel and aluminum are present together in the alloy and when the nickel content exceeds 3 percent. Our experiments have shown that at least 3 percent nickel must be present with at least 0.5-percent aluminum to obtain an alloy that can be hardened satisfactorily by'heat treatment at low temperatures. If the aluminum is omitted, little or no hardening is obtained by heat treatment at low temperatures- If the cadmium is omitted, the resistance of. the alloy to attack by corrosive agents and especially to intergranular attack by steam is lowered con.- .siderably.

Consequently, if one desires to obtain a corrosion resistant .alloy whichds also capable of being hardened satisfactorily by low temperature heat treatment, he must select from the following composition range:

Percent Copper 60. to 95.95 Cadmium .05 to 2.0 Nickel 3.0 to 30.0 Aluminum .5 to 3.0 Zinc l .5 to 36.45

For improving the soundness of the castings manganese may be added from .01 to about 1 percent.

If one desires only excellent corrosion resistance in an alloy of moderate strength and hardness but which cannot be hardened to any great extent by precipitation, the following composition range is suitable.

Percent Copper 60. to 98.7 Cadmium .05 to 2.0 Nickel 15 to 2.5 Aluminum .25 to 3.0 Zinc .5 to 39.2

For improving the soundness of the castings manganese may be added from .01 to about 1 percent.

In view of the fact. that our improvement includes several copper nickel aluminum zinc cadmium alloys, it is dificult to state any single preferred alloy in the group. However, for informative purposes we are listing a few of the most important alloys which have ben specifi cally improved by ourinvention, The composition of five of these alloys that can be readily cold worked and '(cr)' hardened by heat treatment at low temperatures, if'desired, are now given. For example:

When manganese is added these alloys would be approximately as follows.

(a) (c) (a) I (o- Percent Percent Percent Percent Percent Copper 65.0 65. 0 92.0 68.0 I 68. 0 0.5 0.5 0.5 0.5 0.5 18. 0 5. 0 5. 0 l0. 0 l5. 0 l. 5 1. 5 l. 5 1. 5 2. 0 14. 27. 95 19. 92 14. Manganese 0. l5 0. 05 0. 05 0.08 0. 1

Improved alloys of this type, either with or without the manganese, containing more than 60% copper that have been work hardened by drawing or rolling can be softened by annealing at approximately 825 C. and quenching in cold water. The annealed or work hardened metal, whether in the form of sheet, rod,tube, et al., can be readily fabricated into the finished product and then hardened to the extent desired by a suitable heat treatment in the range of temperatures approximately 300 C. to 550 C. This property of being hardenable is especially valuable for such articles as nuts,bolts, fuse bodies, primers, nipples, valves, springs, wire screens, hinges,

chains-jewelry, tableware, coins, keys and clock parts.

Some of these improved alloys can be readily cold worked but cannot be hardened or only to a slight extent by precipitation at low tempera tures. Such alloys are within substantially the following ranges.

Zinc

When manganese is added to either of these groups it will be approximately from 0.01% to 1%. Examples of specific alloys within these ranges which we have found to'be particularly useful are approximately as follows:

Percent Percent Percent Percent Percent Copper 68. 0 68.0 65. 0 65.0 68. 0 Cadmium 0.5 0.5 0.5 0.5 0.5 Nickel 17.0 10.0 5.0 2.0 1.0 Aluminum 0. 25 0. 25 0. 25 0. 4 1. 0 Zinc 14.25 21. 25 29. 25. 32. 1 29.5

When manganese is added these alloys would be approximately as follows:

(a) (b)- (c) Percent Percent Percent PUCMIZ Percent Copper 68.0 68.0 65.0 65.0 68.0 Cadmium. 0. 5' 0. 5 0. 5 0.5 0. 5 Nickel. 17. 0 10. 0 5. 0 2. 0 1.0 Aluminum.- 0. 25 0. 25 0. 25 0. 4 l. 0 Zinc 14. 20 21. 23 29. 24 32. 09 29. 49 Manganese.. 0. 05 0.02 0. 01 0.01 0.01

Having thus set'forth the nature of our invention, what we claim is:

1. An alloy comprising copper, cadmimn, nickel; zinc and aluminum in proportions within the] following ranges: Percent Copper 60. to 98.7 Cadmium .05 to 3.0 Nickel .5 -to 30.0 Aluminum .25 to 4.0 Zinc -1 .5 to39.2 Ma.nganese .0.' to 1.0

. said alloy being characterized by superior re-' 'sistance to intercrystalline attack or corrosion when exposed to steam or hot water.

2. An age hardenable copper base alloy characterized by superior resistance to intergranular attack when stressed or unstressed in steam wherein the improved hardness is obtained by heat treatment at temperatures ranging from 300 C. to 550 C. comprising amounts of copper, cadmium, nickel, zinc and aluminum in proportions substantially within the following ranges:

v I Percent Copper; 60. to 95.95 Cadmium .05 to 2.0. Nickel 7 3.0 to 30.0 Aluminum .5 to 3.0

Zinc .5 to 36.45

- num, and 15% zinc.

3. A heat treatable copper-zinc alloy containing from .5-to 36'.% zinc, .05 to 3.0% cadmium, 3. to 30.0% nickel, and .5 to 3.0% aluminum, and

balance substantially copper, and the nickel con-- tent being at least 3 times the alumium content, wherein improved hardness is obtained by heating. the alloy to the neighborhood of 750 C. to

900 C., rapidly cooling and reheating to a temperature of about 300 C. to 550 C., and said alloy being characterized by superior resistance to intercrystalline attack or corrosion when exposed to steam or hot water.

4. A heat treated and artificially aged copperbase alloy containing from .5.to 36.% zinc, .05

to 3.0% cadmium, 3. to 30.0% nickel and .5 to 3.0% aluminum, the balance of the alloy consisting principally of copper and the nickel content being at least three times the aluminum content, wherein improved hardness is obtained by heating the alloy to the neighborhood of 750 C. to.-

900 C., rapidly cooling, cold working and reheating. to-a temperature of about 300 C. to 550. C., and said alloy being characterized by superior resistance to intergranular attack when exposed to steam or hot water.

5. An alloy composed of copper, cadmium, nickel, zinc and aluminum in proportions within the following ranges:

, Percent Copper 60. to 95.95 Cadmium .05 to 2.0 Nickel 3.0 to 30.0 Aluminum j .5 to 3.0 Zinc 15 to 36.45

6. An alloy comprising approximately copper, 5% nickel, 0.5% cadmium, 1.5% aluminum, and 28.% zinc.

'7. An alloy comprising approximately 92% copper, 5% nickel, 0.5% cadmium, 1.5% aluminum and 1% zinc.

' 8. An alloy comprising approximately 65% copper, 18% nickel, 0.5% cadmium, 1.5% alumi- 9. An alloy characterized by superior resistance to softening in service in steam and other atmospheres at temperatures up to 500 C. composedof from 0.5 to 36% ,zinc, 0.05 to3% cadmium, 3 to 30% nickel, 0.5 to 3% aluminum, and the balance substantially copper.

CHARLES H. DAVIS.

ELLEER L. MUNSON. 

